1. Field of the Invention
The present invention relates to a scaling process system which optimally carries out a scaling process of an image, a video output apparatus and a replay apparatus.
2. Description of Related Art
There are various types of formats such as NTSC (National Television System Committee), PAL (Phase Alternating Line), high-vision, personal computer signal and the like for video signals. When video signals of such various types of formats are to be displayed in a display which has various numbers of pixels, there is a need to carry out a scaling process to convert the signal format in accordance with the number of pixel of each display.
Conventionally, as a between-pixel interpolation method which is a technique of scaling process of a digital video, for example, a linear interpolation method, a three-dimensional interpolation method, a spline interpolation method and the like are known. In these methods, pixels which are uniformly processed by an interpolation filter from neighboring pixels are added between the original pixels.
For example, when scaling process is carried out between a DVD (Digital Versatile Disc) recorder and an AV (Audio Visual) device such as a television receiver, in general, there is known a method to carry out the scaling process in the DVD recorder side and a method to carry out the scaling process in the television receiver side. Here, there is a need to determine by which one of the two devices the scaling process is to be carried out.
In view of the above matter, there is developed a technique to determine by which one of the two devices the scaling process is to be carried out (for example, see JP 2008-259180).
In such determination, ideally, a device which can execute the most high-performance scaling process is to be selected among devices.
Comparison of superiority/inferiority of scaling performance which can be determined by a numerical value such as a resolution is easy. However, there is no unequivocal evaluation method for between-pixel interpolation method and the method is generally subjectively decided. Even in JP 2008-259180, there is a possibility that the most optimal scaling process is not necessarily carried out because a particular setting of criteria for judgment regarding between-pixel interpolation method is not disclosed.